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Made a video showing my own development on EGT sensors, have run these things for a long time (mid 1990's) and tested a bit back in the 'dark ages' revisiting some of the very old log files showed up some interesting information.

I found there is much scope for improvement with regards to the following

• Accuracy

• Response

• Durability

In the pure EGT probes available (not fine wire) there is over a 200deg C variance I have personally measured, this has a large impact on TIT. Many times taking off a turbine housing to see the blades in distress its now obvious that the reported temperature is simply that of the probe and not of the gas it is sampling. Over the last few months dealing with the reputable names in TC industry it was often stated to me that "we sell these to companies with test cells who supply race power trains (engines and electronics) and no one questions the readings" these are people who supply DPI, WEC, F1, WRC, level competitors.

https://www.youtube.com/watch?v=GXbO9O8 ... ivNz_nRGzR



^ check out the clip above ^

https://www.youtube.com/watch?v=u7_4DJf ... e=youtu.be



^ here you go.
I hope people find this of use, it was interesting for me to learn about it some more.

So from the colour chart...is the fast one reading high ?

Good video, I had asked many times before...how do we actually test or calibrate thermocouples, rather than just hoping they read correctly.

But always knew TC's are pretty slow, even though I'd seen other people claim they are very fast...errr nope, they arent, by design they cant be

stevieturbo wrote: ↑Wed Dec 18, 2019 11:26 pm So from the colour chart...is the fast one reading high ?

Good video, I had asked many times before...how do we actually test or calibrate thermocouples, rather than just hoping they read correctly.

But always new TC's are pretty slow, even though I'd seen other people claim they are very fast...errr nope, they arent, by design they cant be

Thanks mate

I try, the highest reading one is the thinnest wire type, the names of the channels and temps are at the 4:05 mark in the video for reference.
got a couple of customers sending me their prior spec (new) probes back and I will just fix them up in jig and change out egt1, position the 1.50mm x 30mm and the fine wire right next to it and run the test again to show in real time what the differences are. Its shocking to see how under reported the miss designed EGT probes can be. Nice theory, but in reality they just don't work

For calibration that is a good question, the maker of the gas set up I use says the peak flame temperature on butane and air is 1350deg C, the highest I have recorded on fine wire type K is 1345deg C (it does vary depending on ambient pressure, and assuming fully charge gas pressure). To give you an idea of probe variation, some in 1/4" open element will not read above 950 deg C @ ROC = 0......... that is a 400deg C offset !

Under estimated how popular they would be, all gone in one day!
I think allot of people are shocked to see just how poor all the other EGT probes out there are compared to these

stevieturbo wrote: ↑Wed Dec 18, 2019 11:26 pm Good video, I had asked many times before...how do we actually test or calibrate thermocouples, rather than just hoping they read correctly.

I'd seen other people claim they are very fast...errr nope, they arent, by design they cant be

Yeah its not that hard to do a valid test.

I guess either,
A) Response: 'they' have done the test and don't want to disclose the real truth as who else would take the time to disprove or otherwise contradict them?
B) Accuracy: bombard you with the std replies of once its stabilized they all read the same (which they do not)

Through my own research on this I did find some published papers which describe the effect of where the voltage is generated in the TC, and its not at the tip/junction rather a way down further from the saturated point (which by color indicates the same temp give or take). In short without boring people too much at/near the measurement zone (from my own work) its the thermal mass of the probe, the wire used to make it, the insulation, and other factors I wont go into that dictate the accuracy once the probe is saturated (ROC = 0).

The size's, materials, and manufacturing details I finally selected were tested to strike the best balance of durability, response, and accuracy.

How to use an EGT probe is a whole other topic can they be fast? you bet! just need one design right

How flexible...soft...whatever is the tip, to be exposed in the harsh environment of the exhaust stream ?

stevieturbo wrote: ↑Thu Dec 19, 2019 5:48 pm How flexible...soft...whatever is the tip, to be exposed in the harsh environment of the exhaust stream ?

It's high in strength, I did experiment with a range of diameters and tip dimensions and one I settled on meets the #1 criteria of durability for the application as EGT. Could make it faster, more accurate, but also realize people don't want to be changing them out unless it physically been hit but a piece of engine so chose the one I did after testing.

p.s. If you look here > http://www.aquamist.co.uk/forum2/vbulle ... #post25027 you can see some of the types I have run over the years, so just exposed wire on rotary exhaust in turbo form ! you would be surprised what will work and for how long.

Next query would be....how fast are they compared to a typical air temp sensor, say like an ATS04 or something ?

stevieturbo wrote: ↑Thu Dec 19, 2019 9:35 pm Next query would be....how fast are they compared to a typical air temp sensor, say like an ATS04 or something ?

I can do a back to back test if you like?
I did do some hot air gun sim for a bloke who wants to use it on compressor outlet. I do have a few fast acting AIT here just have to add a few more wires to the bench harness.

That is basically what I was getting at.

The one I use seems to respond fairly quickly....but I've never compared it back to back with anything ( or side by side )

For places where it could matter the fast thermocouple may be a better option than the regular thermistor air temp sensor ?